Merge branch 'swab' (closes #22)

src/swab.rs

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	env::args,
+	io::{ stdin, stdout, Error, ErrorKind, Read, Write },
+	process::ExitCode,
+	vec::Vec
+};
+
+extern crate getopt;
+use getopt::{ Opt, Parser };
+
+extern crate sysexits;
+use sysexits::{ EX_OK, EX_OSERR, EX_USAGE };
+
+fn oserr(s: &str, e: Error) -> ExitCode {
+	eprintln!("{}: {}", s, e);
+	ExitCode::from(EX_OSERR as u8)
+}
+
+fn usage(s: &str) -> ExitCode {
+	eprintln!("Usage: {} (-f) (-w [wordsize])", s);
+	ExitCode::from(EX_USAGE as u8)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut buf: Vec<u8> = Vec::new();
+	let mut input = stdin();
+	let mut output = stdout().lock();
+
+	let mut opts = Parser::new(&argv, "fw:");
+	let mut force = false;
+	let mut wordsize: usize = 2;
+
+	loop {
+		match opts.next() {
+			None => break,
+			Some(opt) =>
+				match opt {
+					Ok(Opt('f', None)) => force = true,
+					Ok(Opt('w', Some(arg))) => {
+						match arg.parse::<usize>() {
+							Ok(w) if w % 2 == 0 => { wordsize = w; () },
+							_ => { return usage(&argv[0]); },
+						}
+					},
+					_ => { return usage(&argv[0]); }
+				}
+		}
+	}
+
+	buf.resize(wordsize, 0);
+
+	loop {
+		match input.read(&mut buf) {
+			Ok(0) => break ExitCode::from(EX_OK as u8),
+			Ok(v) if v == wordsize => {
+				let (left, right) = buf.split_at(v/2);
+				if let Err(e) = output.write(&right)
+						.and_then(|_| output.write(&left)) {
+					break oserr(&argv[0], e)
+				}
+			},
+			Ok(v) => {
+				if let Err(e) = output.write(&buf[..v]) {
+					break oserr(&argv[0], e)
+				}
+			},
+			Err(e) if e.kind() == ErrorKind::Interrupted && force => continue,
+			Err(e) => break oserr(&argv[0], e)
+		}
+	}
+}